From f336bde91e3fd9c3c2960aa548b8917eb1216678 Mon Sep 17 00:00:00 2001
From: Jakub Martisko <jamartis@redhat.com>
Date: Thu, 6 Feb 2020 15:26:33 +0100
Subject: [PATCH] -c flag

---
 sed/execute.c | 18 +++++++++--
 sed/sed.c     | 20 +++++++++++-
 sed/sed.h     |  4 +++
 sed/utils.c   | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++
 sed/utils.h   |  2 ++
 5 files changed, 127 insertions(+), 3 deletions(-)

diff --git a/sed/execute.c b/sed/execute.c
index c5f07cc..4e5f5b3 100644
--- a/sed/execute.c
+++ b/sed/execute.c
@@ -670,11 +670,25 @@ closedown (struct input *input)
       if (strcmp (in_place_extension, "*") != 0)
         {
           char *backup_file_name = get_backup_file_name (target_name);
-          ck_rename (target_name, backup_file_name);
+          if (copy_instead_of_rename)
+          {
+            ck_fccopy (target_name, backup_file_name, input->out_file_name);
+          }
+          else
+          {
+            ck_rename (target_name, backup_file_name);
+          }
           free (backup_file_name);
         }
 
-      ck_rename (input->out_file_name, target_name);
+      if (copy_instead_of_rename)
+      {
+        ck_fcmove (input->out_file_name, target_name, input->out_file_name);
+      }
+      else
+      {
+        ck_rename (input->out_file_name, target_name);
+      }
       cancel_cleanup ();
       free (input->out_file_name);
     }
diff --git a/sed/sed.c b/sed/sed.c
index 1ca5839..745159e 100644
--- a/sed/sed.c
+++ b/sed/sed.c
@@ -67,6 +67,10 @@ bool debug = false;
 /* How do we edit files in-place? (we don't if NULL) */
 char *in_place_extension = NULL;
 
+/* Do we use copy or rename when in in-place edit mode? (boolean
+ +   value, non-zero for copy, zero for rename).*/
+int copy_instead_of_rename = 0;
+
 /* The mode to use to read/write files, either "r"/"w" or "rb"/"wb".  */
 char const *read_mode = "r";
 char const *write_mode = "w";
@@ -170,6 +174,10 @@ Usage: %s [OPTION]... {script-only-if-no-other-script} [input-file]...\n\
 #endif
   fprintf (out, _("  -i[SUFFIX], --in-place[=SUFFIX]\n\
                  edit files in place (makes backup if SUFFIX supplied)\n"));
+
+  fprintf(out, _("  -c, --copy\n\
+                 use copy instead of rename when shuffling files in -i mode\n"));
+
 #if O_BINARY
   fprintf (out, _("  -b, --binary\n\
                  open files in binary mode (CR+LFs are not" \
@@ -214,7 +222,7 @@ specified, then the standard input is read.\n\
 int
 main (int argc, char **argv)
 {
-#define SHORTOPTS "bsnrzuEe:f:l:i::V:"
+#define SHORTOPTS "bcsnrzuEe:f:l:i::V:"
 
   enum { SANDBOX_OPTION = CHAR_MAX+1,
          DEBUG_OPTION
@@ -228,6 +236,7 @@ main (int argc, char **argv)
     {"file", 1, NULL, 'f'},
     {"in-place", 2, NULL, 'i'},
     {"line-length", 1, NULL, 'l'},
+    {"copy", 0, NULL, 'c'},
     {"null-data", 0, NULL, 'z'},
     {"zero-terminated", 0, NULL, 'z'},
     {"quiet", 0, NULL, 'n'},
@@ -306,6 +315,10 @@ main (int argc, char **argv)
           follow_symlinks = true;
           break;
 
+        case 'c':
+          copy_instead_of_rename = true;
+          break;
+
         case 'i':
           separate_files = true;
           IF_LINT (free (in_place_extension));
@@ -376,6 +389,11 @@ main (int argc, char **argv)
         }
     }
 
+  if (copy_instead_of_rename && in_place_extension == NULL)
+    {
+      fprintf (stderr, _("Error: -c used without -i.\n"));
+      usage(4);
+    }
   if (!the_program)
     {
       if (optind < argc)
diff --git a/sed/sed.h b/sed/sed.h
index 1c8e83a..0859e72 100644
--- a/sed/sed.h
+++ b/sed/sed.h
@@ -236,6 +236,10 @@ extern countT lcmd_out_line_len;
 /* How do we edit files in-place? (we don't if NULL) */
 extern char *in_place_extension;
 
+/* Do we use copy or rename when in in-place edit mode? (boolean
+   value, non-zero for copy, zero for rename).*/
+extern int copy_instead_of_rename;
+
 /* The mode to use to read and write files, either "rt"/"w" or "rb"/"wb".  */
 extern char const *read_mode;
 extern char const *write_mode;
diff --git a/sed/utils.c b/sed/utils.c
index 9576dd1..371d5a9 100644
--- a/sed/utils.c
+++ b/sed/utils.c
@@ -25,6 +25,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <limits.h>
+#include <fcntl.h>
 
 #include "binary-io.h"
 #include "unlocked-io.h"
@@ -400,7 +401,92 @@ ck_rename (const char *from, const char *to, const char *unlink_if_fail)
   panic (_("cannot rename %s: %s"), from, strerror (errno));
 }
 
+/* Downstream -c related functions */
 
+/* Panic on failing unlink */
+void
+ck_unlink (const char *name)
+{
+  if (unlink (name) == -1)
+    panic (_("cannot remove %s: %s"), name, strerror (errno));
+}
+
+/* Attempt to unlink denoted file if operation rd failed. */
+static int
+_unlink_if_fail (int rd,const char * unlink_if_fail)
+{
+  if (rd == -1 && unlink_if_fail)
+    {
+      int save_errno = errno;
+      ck_unlink (unlink_if_fail);
+      errno = save_errno;
+    }
+
+  return rd != -1;
+}
+
+/* Copy contents between files. */
+static int
+_copy (from, to)
+  const char *from, *to;
+{
+  static char buf[4096];
+
+  FILE *infile, *outfile;
+  int c, retval = 0;
+  errno = 0;
+
+  infile = fopen (from, "r");
+  if (infile == NULL)
+    return -1;
+
+  outfile = fopen (to, "w");
+  if (outfile == NULL)
+    {
+      fclose (infile);
+      return -1;
+    }
+
+  while (1)
+    {
+      size_t bytes_in = fread (buf, 1, sizeof (buf), infile);
+      size_t bytes_out;
+      if (bytes_in == 0)
+        {
+          if (ferror (infile))
+            retval = -1;
+          break;
+        }
+
+      bytes_out = fwrite (buf, 1, bytes_in, outfile);
+      if (bytes_out != bytes_in)
+        {
+          retval = -1;
+          break;
+        }
+    }
+
+  fclose (outfile);
+  fclose (infile);
+
+  return retval;
+}
+
+/* Attempt to copy file contents between the files. */
+void
+ck_fccopy (const char *from,const char *to, const char *unlink_if_fail)
+{
+   if (!_unlink_if_fail (_copy (from, to), unlink_if_fail))
+   panic (_("cannot copy %s to %s: %s"), from, to, strerror (errno));
+  }
+
+/* Copy contents between files, and then unlink the source. */
+void
+ck_fcmove (const char *from, const char *to,const char *unlink_if_fail)
+{
+   ck_fccopy (from, to, unlink_if_fail);
+    ck_unlink (from);
+}
 
 
 /* Implement a variable sized buffer of `stuff'.  We don't know what it is,
diff --git a/sed/utils.h b/sed/utils.h
index 47a029e..0aba107 100644
--- a/sed/utils.h
+++ b/sed/utils.h
@@ -40,6 +40,8 @@ size_t ck_getdelim (char **text, size_t *buflen, char buffer_delimiter,
 FILE * ck_mkstemp (char **p_filename, const char *tmpdir, const char *base,
                    const char *mode) _GL_ARG_NONNULL ((1, 2, 3, 4));
 void ck_rename (const char *from, const char *to);
+void ck_fccopy (const char *from, const char *to, const char *unlink_if_fail);
+void ck_fcmove (const char *from, const char *to, const char *unlink_if_fail);
 
 void *ck_malloc (size_t size);
 void *ck_realloc (void *ptr, size_t size);
-- 
2.24.1

